A new discovery pinpoints the part of the brain that triggers fear relapse, a finding that could advance the treatment of disorders like post-traumatic stress disorder.

“Patients often undergo exposure therapy to reduce their fear of situations and stimuli associated with trauma,” says Steve Maren, professor of psychological and brain sciences at Texas A&M University.

“Although exposure therapy is often effective, pathological fear and anxiety are known to return or relapse under a number of circumstances. This often occurs, for example, when trauma-related stimuli, which have come to be tolerated during therapy, are unexpectedly experienced outside of the clinical context.

“Relapse of fear after therapy has been estimated to occur in upwards of two-thirds of patients undergoing exposure therapy.”

As reported in Nature Neuroscience, Maren and colleagues studied the relationship between three parts of the brain: the hippocampus, which is involved in memory; the prefrontal cortex, which is involved in executive control and regulation; and the amygdala, which is involved in emotion.

While the neurocircuit between the three have long been known to process fear, the current study pinpoints connections between the hippocampus and a specific type of cell in the prefrontal cortex that is involved in a relapse of fear.

“This has wide-spread implications for treating fear disorders in the future, as we now know what part of the brain to target,” says graduate student Travis Goode.

Other researchers from Texas A&M and from Sah Laboratory in Australia are coauthors of the work.